Abstract: A process for the production of urea wherein: production of pure urea (U) includes the concentration of an aqueous urea solution (23) by crystallization; a urea crystallization purge aqueous phase (32) comprising urea, water and biuret, which is purged from the urea crystallization process, is used in a high-biuret urea processing section (34) for additional production of urea with a high content of biuret.

Abstract: A process of prilling of a urea melt comprising the use of calcium lignosulfonate or carboxymethyl starch as additive to obtain a formaldehyde-free urea product.

Abstract: A process for the production of biuret from urea wherein: a urea aqueous solution (24) withdrawn from the recovery section of a urea plant is processed to remove water and obtain a concentrated urea melt (25); said urea melt is processed under biuret-forming conditions to decompose urea into biuret and ammonia and obtain a high-biuret urea melt (26); said high-biuret urea melt (26) is diluted with water or with an aqueous stream obtaining a solution (28); the solution (28) is subject to crystallization and precipitation of a solid phase containing biuret which is separated from the aqueous phase.

Abstract: A process for the production of feed grade urea starting from a liquid urea melt, the process comprising processing the urea melt (6) to promote the formation of biuret until a concentration of at least 3% biuret, and subjecting the so obtained biuret-containing urea melt (8) to a shaping process to obtain a granular urea product.

Abstract: A method for revamping an ammonia-urea plant wherein: the ammonia section is modernized to produce an extra amount of low pressure steam; condensation stage of the high-pressure urea synthesis loop is modified to use part of the condensation heat of the urea stripper vapours to produce medium-pressure steam, said medium-pressure steam is fed to one or more steam users of the urea section, particularly for carbamate decomposition, the input of low-pressure steam to the urea section is balanced by importing the extra low-pressure steam produced in the ammonia section.

Abstract: Use of a ferritic stainless steel containing at least 23% chromium for the manufacture of components of the high-pressure urea synthesis section of a urea plant.

Abstract: A process for synthesis of urea from ammonia and carbon dioxide comprising the synthesis of urea in parallel in a first urea reactor (1) at a first urea synthesis pressure and in a second urea reactor (2) at a second and lower urea synthesis pressure; a stripping step of the reaction effluent of the first reactor, which is performed in a stripper (4) operating at a stripping pressure lower than the first urea synthesis pressure; the reaction effluent (21) of the second reactor (2) and the stripper liquid effluent (11) are sent to a recovery section (13) where a carbamate-containing recycle solution (17) is produced, and said recycle solution (17) is sent partly to said first reactor and partly to said second reactor.

Abstract: A process for synthesis of urea from ammonia and carbon dioxide wherein: the urea synthesis is performed with a stripping process in a synthesis loop including at least a reactor (1), a stripper (2) and a condenser (3); the reactor effluent is treated in the stripper to remove unreacted ammonia and carbon dioxide; the urea solution (14) from the stripper is sent to a low-pressure recovery section (4); the stripper vapours are split into a first portion (151) directed to the reactor and a second portion (152) sent to the condenser; the condenser (3) is a shell-and-tube kettle condenser where condensation of stripper vapours is performed in the tube side (30); a carbamate-containing effluent (20) from the condenser is returned to the reactor.

Abstract: A process for purifying a urea-containing aqueous stream, such as the aqueous stream from the recovery section of a urea plant, comprising a step of removing biuret from the urea-containing stream by reverse osmosis in one or more reverse osmosis stages.

Abstract: A process for synthesis of urea from CO2 and NH3 wherein a steam flow (13) produced in the condenser (3) of a high-pressure synthesis loop is compressed to raise its pressure and temperature before using the steam as a heat source for a downstream step of the process.

Abstract: A reactor for the synthesis of urea comprising a vertical shell and perforated baffles or trays (3) arranged to define compartments of the reactor, wherein each baffle comprises an array of individual perforated tiles (10) wherein each tile (101) comprises side walls (101A-101D) and a top face (101F), the side walls having first perforations for the liquid and said top face having second perforations for the gas, wherein said second perforations are smaller than said first perforations, and the tiles are distributed over the baffle with a two-dimensional pattern where adjacent tiles are separated by gaps (17).

Abstract: A method for controlling a prilling bucket in the prilling of a a urea melt (UM) including: feeding the urea melt to a prilling bucket (1) which vibrates under the action of a magnetostrictive device (2), wherein the vibration of the bucket is controlled, as a function of the amount of urea melt to be prilled, by the following steps: acquisition of a time-varying input signal (3) which represents the flow rate of urea melt fed to the prilling bucket; generation of a first signal (5) and of a second signal (6), independently from each other, as a function of said input signal (3); generation of a third signal (10) having a frequency which is modulated by said first signal and an magnitude which is modulated by said second signal, and use of said third signal to drive said magnetostrictive device (2).

Abstract: A method for controlling a prilling bucket in the prilling of a a urea melt (UM) including: feeding the urea melt to a prilling bucket (1) which vibrates under the action of a magnetostrictive device (2), wherein the vibration of the bucket is controlled, as a function of the amount of urea melt to be prilled, by the following steps: acquisition of a time-varying input signal (3) which represents the flow rate of urea melt fed to the prilling bucket; generation of a first signal (5) and of a second signal (6), independently from each other, as a function of said input signal (3); generation of a third signal (10) having a frequency which is modulated by said first signal and an magnitude which is modulated by said second signal, and use of said third signal to drive said magnetostrictive device (2).

Abstract: A process for synthesis of urea from ammonia and carbon dioxide comprising the synthesis of urea in parallel in a first urea reactor (1) at a first urea synthesis pressure and in a second urea reactor (2) at a second and lower urea synthesis pressure; a stripping step of the reaction effluent of the first reactor, which is performed in a stripper (4) operating at a stripping pressure lower than the first urea synthesis pressure; the reaction effluent (21) of the second reactor (2) and the stripper liquid effluent (11) are sent to a recovery section (13) where a carbamate-containing recycle solution (17) is produced, and said recycle solution (17) is sent partly to said first reactor and partly to said second reactor.

Abstract: A process of granulation of a urea melt, comprising: adding a first additive containing carboxymethyl starch to one or more first stage(s) of the granulation process, to form a carcarboxymethyl starch containing inner layer of urea granules, and adding a second additive containing calcium lignosulfonate to one or more second stage(s) of the granulation process, downstream said first stages, to form granules with a coating containing calcium lignosulfonate.

Abstract: A process for synthesis of urea from CO2 and NH3 wherein a steam flow (13) produced in the condenser (3) of a high-pressure synthesis loop is compressed to raise its pressure and temperature before using the steam as a heat source for a downstream step of the process.

Abstract: A process of granulation of a urea melt, comprising: adding a first additive containing carboxymethyl starch to one or more first stage(s) of the granulation process, to form a carboxymethyl starch containing inner layer of urea granules, and adding a second additive containing calcium lignosulfonate to one or more second stage(s) of the granulation process, downstream said first stages, to form granules with a coating containing calcium lignosulfonate.